/// <summary>
/// Builds the Planes so that they make up the left, right, up, down, front and back of the Frustum
/// </summary>
public void UpdateFrustum(Matrix4 projectionMatrix, Matrix4 modelviewMatrix)
{
Matrix4 clipMatrix = modelviewMatrix * projectionMatrix;
planes[0] = new Plane(clipMatrix[0].w - clipMatrix[0].x, clipMatrix[1].w - clipMatrix[1].x, clipMatrix[2].w - clipMatrix[2].x, clipMatrix[3].w - clipMatrix[3].x);
planes[1] = new Plane(clipMatrix[0].w + clipMatrix[0].x, clipMatrix[1].w + clipMatrix[1].x, clipMatrix[2].w + clipMatrix[2].x, clipMatrix[3].w + clipMatrix[3].x);
planes[2] = new Plane(clipMatrix[0].w + clipMatrix[0].y, clipMatrix[1].w + clipMatrix[1].y, clipMatrix[2].w + clipMatrix[2].y, clipMatrix[3].w + clipMatrix[3].y);
planes[3] = new Plane(clipMatrix[0].w - clipMatrix[0].y, clipMatrix[1].w - clipMatrix[1].y, clipMatrix[2].w - clipMatrix[2].y, clipMatrix[3].w - clipMatrix[3].y);
planes[4] = new Plane(clipMatrix[0].w - clipMatrix[0].z, clipMatrix[1].w - clipMatrix[1].z, clipMatrix[2].w - clipMatrix[2].z, clipMatrix[3].w - clipMatrix[3].z);
planes[5] = new Plane(clipMatrix[0].w + clipMatrix[0].z, clipMatrix[1].w + clipMatrix[1].z, clipMatrix[2].w + clipMatrix[2].z, clipMatrix[3].w + clipMatrix[3].z);
for (int i = 0; i < 6; i++)
{
float t_mag = planes[i].Normal.Length;
planes[i].Scalar /= t_mag;
planes[i].Normal /= t_mag;
}
}
/// <summary>
/// Builds a duplicate plane
/// </summary>
/// <param name="_Plane">Plane to duplicate</param>
public Plane(Plane plane)
{
normal = plane.Normal;
scalar = plane.Scalar;
}
/// <summary>
/// Builds a new Frustum and initializes six new planes
/// </summary>
public Frustum()
{
planes = new Plane[6];
for (int i = 0; i < 6; i++) planes[i] = new Plane(0, 0, 0, 0);
}
/// <summary>
/// Returns the position of the AxisAlignedBoudingBox relative to a plane
/// </summary>
/// <param name="p">Plane to test</param>
/// <returns>Negative, Positive or Both sides of plane</returns>
public Plane.PlaneSide Intersects(Plane p)
{
return p.Intersects(this);
}